The invention relates to an expansible plastic fixing plug having a slot extending for a part of its length and a longitudinal bore for insertion of a fixing screw or similar means.
A known expansible plastic fixing plug has a plastic body with a slot starting at its front end and extending for a part of its length, the slot being in the form of a split between two halves of the body in the front region of the plug. The expansible plastic fixing plug has a longitudinal bore starting from the rear end of the fixing plug for insertion of a fixing screw or similar means. This bore has a cylindrical portion and following it a narrowing portion which terminates at the slot.
German Patent 1 097 117 discloses a cylindrical expansible plastic fixing plug which is slotted for a part of its length, the rear end of which has a longitudinal bore for the insertion of a fixing screw. The first portion of this longitudinal bore is cylindrical in form and has an inner diameter corresponding approximately to the outer diameter of the fixing screw. The first portion of this longitudinal bore is cylindrical in form and has a diameter corresponding approximately to the outer diameter of the fixing screw. Adjoining this cylindrical portion there is a conically tapering or narrowing portion, which terminates in the slot of the fixing plug formed by a split in the front region of the plug. The conical taper of the longitudinal bore of the fixing plug provides a circular cross-sectional narrowing which presents a high insertion resistance as the fixing screw is screwed in. Although the expansible segments of the fixing plug formed by the longitudinal slot are to yield at right angles to the plane of the slot to reduce the insertion resistance, in the plane of the slot the thread of the fixing screw must nevertheless cut fully into the material of the fixing plug. Because the fixing plug is unable to expand in the plane of the slot, this increased insertion resistance is not converted into corresponding expansion force. Because of the increased insertion resistance it is possible, particularly in the case of drilled holes that have turned out to be too big, for the fixing plug to turn with the fixing screw as this is screwed in, despite antirotation ribs arranged on the outer circumference of the plug.